Neb. Rev. Stat. § 42-747.04

A party or support enforcement agency seeking to modify, or to modify and enforce, a foreign child-support order not under the Convention may register that order in this state under sections 42-736 to 42-743 if the order has not been registered. A petition for modification may be filed at the same time as a request for registration, or at another time. The petition must specify the grounds for modification.